The Height of Surface Layer Observed by Doppler Lidar in a Coastal Area of Tokyo

In this study, we propose a new height parameter representing the top of the surface layer based on two Doppler lidar observations in a coastal area of Tokyo. We estimated the surface layer height from the vertical momentum flux distribution, which is defined as the height where upper-extrapolated value of the linearly decreasing Reynolds stress becomes zero. As for this parameter, following results are obtained from the field experiment.

1)The height of the surface layer, which is defined in this study, increases with increasing wind speed. This is probably because strong horizontal shear generated large eddy structure.

2)The height of the surface layer became always lower than the atmospheric boundary layer (ABL) height. In daytime, ABL height is always higher than that of the surface layer since ABL height is almost same as the top of the mixed layer. In the nighttime, there is no mixed layer and the ABL height become equivalent to surface layer height.

3)Diurnal variation of the height of the surface layer and that of the ABL are negatively correlated.

These results were further examined using a tower measurement located in the same area as the present observation.